Recursive method for determining frequency factors in interstratified clay diffraction calculations.

A recursive algorithm is suggested for calculating frequency factors. The method is so-named because the factors for a given separation are taken to be functionally dependent on more easily calculated factors for smaller separations, leaving elements on both sides of the derived equalities. The computational advantage is gained by treating groups of permutations of the clay layers at once, instead of treating each possible sequence individually. The effort required in the calculation only increases linearly with the number of layers in the sequences, N, allowing the consideration of larger crystallites and the use of smaller computers than was previously possible. -J.M.H.